Apparatus and method for internally coating live gas pipe joints or other discontinuities

Abstract

Joints or other discontinuities in live gas pipelines are sealed by spraying the joint or discontinuity with a coating material by means of an explosion-proof coating device, capable of traversing long lengths of pipe. The coating device is inserted into the pipe and uses a halogen lit explosion-proof camera for locating joints or other discontinuities in the pipe. The preferred coating material is a high build epoxy-type elastomeric polyurethane, which quickly cures in the presence of pressurized flowing gas. Several joints or discontinuities, spanning several hundred feet of pipe, may be coated using a single excavation.

What is claimed is: 
     
       1. A system for internally coating a joint or other discontinuity in a live gas pipeline comprising: (a) an entry unit having an orifice, wherein said entry unit is operatively connected to a pipeline;   (b) a flexible conduit slidingly engaged with said orifice of said entry unit;   (c) a propulsion unit removably connected to said flexible conduit for propelling said flexible conduit through said pipeline; and   (d) a coating unit removably connected to said flexible conduit, wherein said coating unit applies an adhesive material to an interior surface of said pipeline in the presence of a pressurized gas.   
     
     
       2. The system as claimed in claim 1 wherein said entry unit is a split sleeve dresser having at least one entry port. 
     
     
       3. The system as claimed in claim 1 wherein said entry unit is a gate valve. 
     
     
       4. The system as claimed in claim 1 wherein said entry unit is a curved conduit having a gate valve. 
     
     
       5. The system as claimed in claim 1 wherein said propulsion unit comprises: (a) a first end and a second end, an inner surface and an outer surface;   (b) a motor removably connected to said outer surface;   (c) a control device operatively connected to said motor; and   (d) a plurality of flywheels engagedly powered by said motor, wherein said flywheels tangentially engage said flexible conduit so as to produce and control lateral movement of said conduit.   
     
     
       6. The system as claimed in claim 1 wherein said flexible conduit is a hollow containment tube having a plurality of dedicated conduits. 
     
     
       7. The system as claimed in claim 1 wherein said coating unit comprises: (a) a carriage having a first end and a second end;   (b) a spraying mechanism detachably connected to said first end of said carriage; and   (c) a plurality of adjustable legs, each having a first end and a second end, said first end slidably connected to said carriage.   
     
     
       8. The system as claimed in claim 7 wherein said coating unit further comprising: (a) rolling members rotatably connected to said second end of said adjustable legs; and   (b) a monitoring device detachably connected to said centering carriage.   
     
     
       9. The system as claimed in claim 8 wherein said monitoring device is a sealed explosion-proof camera probe. 
     
     
       10. The system as claimed in claim 1 further comprising an adhesive material, which is applied to the interior of a gas pipe by said coating unit. 
     
     
       11. The system as claimed in claim 10 wherein said adhesive material hardens in a gas environment and wherein said hardened material is substantially impervious to said gas. 
     
     
       12. The system as claimed in claim 10 wherein said adhesive material hardens in a gas free environment. 
     
     
       13. The system as claimed in claim 10 wherein said adhesive material hardens in an oxygen rich environment. 
     
     
       14. The system as claimed in claim 10 wherein said adhesive material hardens in an oxygen free environment. 
     
     
       15. The system as claimed in claim 10 wherein said adhesive material is a polyoxyethylene polypropylene polymer. 
     
     
       16. The method as claimed in claim 10 wherein said adhesive material is an elastomeric polyurethane. 
     
     
       17. The system as claimed in claim 1 wherein said propulsion unit is removably connected to said entry unit.